POS1414 RISK OF CANCER IN CONNECTIVE TISSUE DISORDERS IN THE NORTH EAST OF ITALY OVER 15 YEARS OF FOLLOW-UP
Authors: E. Treppo, F. Toffolutti, V. Manfrè, M. Taborelli, S. De Vita, D. Serraino, L. Quartuccio
Journal: Annals of the Rheumatic Diseases (2022)

Background Connective tissue diseases (CTD) include systemic lupus erythematosus (SLE), Sjögren’s syndrome (SS), systemic sclerosis (SSc), polymyositis (PM), and dermatomyositis (DM). CTD are characterized by dysfunction of the immune system that leads to the loss of tolerance to self-antigens [1]. Shared genetics, environmental factors, medical treatment of autoimmune diseases and dysregulated immune function have led to speculation of an elevated cancer incidence in patients with autoimmune diseases [2]. Objectives The present study aimed to evaluate the cancer risk associated with the most relevant CTD in the northern Italian region of Friuli Venezia Giulia over the years 2002-2017. The primary objective was to determine whether the risk of malignancy was higher among these rheumatic conditions than the age- and sex-corresponding general population. Methods A retrospective population-based cohort study was conducted using data from healthcare databases of the Friuli Venezia Giulia region, north-east of Italy (1,206,000 inhabitants). Information on demographic characteristics, hospital discharges, exemption from medical charges, drug prescriptions, were individually matched with data from the population-based cancer registry. The cancer risk was assessed in people diagnosed with the following diseases: SLE, SS, SSc, PM, and DM. To compare the cancer incidence in the cohort with the general population, Standardized Incidence Ratios (SIRs) were calculated as the ratio between the observed and the expected number of cancer cases. The cohort included subjects resident in the Friuli Venezia Giulia region, diagnosed with at least one of the following diseases: SLE, SSc, SS, DM, and PM. To guarantee the highest homogeneity and comparability of the exemptions codes, the analysis was restricted to the years 2002-2017. Excluding criteria were: (1) follow-up shorter than 90 days; (2) concurrent diagnoses of rheumatoid arthritis (RA), psoriatic arthritis or ankylosing spondylitis; (3) ever use of biologic drug specific to treat RA (with the exception of rituximab), psoriatic arthritis or ankylosing spondylitis. The patients were observed starting from 90 days after the first date when the diagnosis was mentioned in hospital discharges or exemptions, and they were followed until cancer diagnosis, death, change of regional residence, or December 31, 2017, whichever came first. For the aim of this study, we excluded from the analysis NMSC (ICD-10: C44) and diagnoses based on autopsy only or Death Certificate Only. Results 2504 patients were followed-up for a total of 18,006 person-years (median follow-up: 6.8 years). After 5 and 10 years of follow-up, the cumulative cancer incidence was 2.6% and 8.5%, respectively. The most common cancers were breast (n=34), lung (n=24), colon-rectum-anus (n=20), and non-Hodgkin lymphomas (NHL) (n=20). Overall, no excess cancer risk was noted (SIR=0.87, 95% CI: 0.75-1.00), whereas the number of observed NHL cases was more than two-fold significantly higher than expected (SIR=2.52, 95% CI: 1.54-3.89). The subgroup analysis showed a higher risk of NHL among SS patients (SIR=3.84, 95% CI: 1.92-6.87) and SLE patients (SIR=2.69, 95% CI: 0.99-5.84). Conversely, the study population showed a decreased risk for cancers of breast (SIR=0.61, 95% CI: 0.42-0.85) and corpus uteri (SIR=0.21, 95% CI: 0.03-0.77). Conclusion The incidence of NHL was higher among patients with SS and SLE. A careful surveillance for haematological malignancies in these patients is recommended. The lower risk of cancer for breast and corpus uteri in CTD indirectly supports cancer screening programs and highlights the role of the continuous clinical follow-up for these chronic conditions. References [1]Wang, L.; Wang, F.-S.; Gershwin, M.E. Human Autoimmune Diseases: A Comprehensive Update. J. Intern. Med. 2015 , 278 , 369–395. [2]Hemminki, K.; Huang, W.; Sundquist, J.; Sundquist, K.; Ji, J. Autoimmune Diseases and Hematological Malignancies: Exploring the Underlying Mechanisms from Epidemiological Evidence. Semin. Cancer Biol. 2020 , 64 , 114–121. Disclosure of Interests None declared